Hendrik Boom wrote:

> So I did
>     grub-install /ev/sda
> It seemed to go well.
> But when I disconnected the old, small drive, and tried booting,
> it did manage to start bootine, but got stuck in the initramfs conplaining that it could not fine volume group VG1.
> Now that's the volume group that my entire system is on, except for /boot.  It's kind of essential.
> And VG1 is on dev/md1, a currently defective RAID1 whose one good partition is /dev/sda2.

The currently defective RAID sounds concerning. If the raid is
degraded though either of the mirrored drives in the raid are
functional then the data can be rescued.

> Npw the boot process recognised /dev/md1 properly, but coule not find VG1,
> so initramfs tossed me into busybox so as to fix the problem.
>
> The RAID assembles properly, presumably after starting the initramfs
> script, but not VG1.
...
> What should I look into?

What I would do is to boot the netinst ISO and then use it in rescue
mode. Remove the disk you want to remove. That way the system will
be in the configuration desired. Then boot rescue mode.

    https://www.debian.org/releases/stable/amd64/ch08s06.en.html

Follow those instructions. Which is basically to use Expert mode,
Rescue, then mount the drives, chroot into the system. Then from
the chroot reinstall grub. Then reboot. It should boot.

Bob